1. Technical Field
The present invention relates generally to balancing techniques, and more particularly to a method and apparatus for balancing of a motor armature and fan coupled thereto.
2. Background Art
It has been found that the useful life of an apparatus having a rotating body is shortened if the body is unbalanced. For example, if either of an armature of a motor or a load driven thereby, such as a fan, is unbalanced, the armature will tend to vibrate the motor through the bearings in which it is supported, with the degree of vibration being dependent upon the magnitude of the unbalance. This vibration not only results in wear of the bearings but also increases the noise level and decreases the life of the motor.
Balancing systems have been devised which are useful to minimize the unbalance in a rotating part. An example of such a system is disclosed in Nystuen et al U.S. patent application Ser. No. 657,255, filed Oct. 3, 1984, entitled "Method of and Apparatus for Balancing a Rotary Body". The system disclosed therein includes means for supporting the rotating body in first and second spaced bearings and means for rotating the body in the bearings. Means are included for developing signals representing the forces in the first and second bearings during rotation of the body. These signals are coupled to a computer which includes means for summing the forces about a plane in which one of the bearings is disposed to determine the weight and location of a mass which, if added to or removed from the body, would substantially balance the body.
In the past, such balancing systems were utilized to balance individual motor armatures and loads. Each armature was then assembled into a motor and a load coupled thereto. The resulting motor and load system, however, was often poorly balanced even though the individual armature and load were balanced within specified limits due to the random selection and/or position of the assembled components. This poor overall balance, in turn, reduced the effectiveness of the balancing operation to a level which provided only a marginal increase in motor life.